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IOS 10 Exam 2
Sulfonamides, rifampin, nitrofurantion, chloramphenicol
Question | Answer |
---|---|
Sulfonamides MOA | They are analogue of PABA hich binds dihydropeteroate synthase which would normally catalyze the first step of dihydrofolic acid synthesis (purine, thymidine- DNA) |
Trimethoprim MOA | Structural analogue of duhydrofolic acid, it binds the dihydrofolate reductase and inhibits the concversion of dihydrofolate to tetrahydrofolate |
Rifampin MOA | Bacterialcidal binds to the B-subunit of RNA polymerase and inhibits the initation of transcription |
Nitrofurantion MOA | The AB is initially reduced to the ROS which interacts with DNA. At low concentrations it is a bacteriostatic at high it is a bacteriocidal |
Chlorampenicol MOA | Binds to the 50S ribosomal subunit. Bacteriostatic against most organisms but Bactericidal against S. pneumoniae, H. influ, N. meningitis |
Resistance of Sulfonamides | Intrinsic resistance (E. facalis, lactobacilli-auxotrophic for folic acid), aquired resistance via single chromosomal mutation or plasmid mediated, alterations in enzyme, or PABA |
Resistance of trimethoprim | Aquired resistance via chromosomal and plasmid mutation, decreased affinity of enzyme, hyperproduction of dihydrofolate, decrease porin permibility |
Resistance of Rifampin | Aquired mutation-single monotherapy lead to mutation of RNA polymerase B-subunit. ALWAYS USE COMBO DRUG |
Resistance of nitrofurantion | Aquired mutation causes reduced ROS generation or changes in permibility |
Gram + aerobic activity of sulfonamides | Acinomycetes, listeria, nocardia, mycobacteium, staph aureus, strep |
Gram- aerobic activity of sulfonamides | Burkholderia, enterobacteriae, heameophilus, neisseria, pseudomonas, stenotrophomonas |
Anaerobic activity of sulfonamides | bacteroides (not fragilis) Gardenerella |
Atypical activity of Sulfonamides | Chlaymidia, legionella |
Protozian activity of sulfonamides | Acanthamoeba, Pneumocystis, toxoplasma, plasmodium falciparum |
Fungi activity of sulfonamides | Histoplasma capsulatum, paracoccidodes brasilensis |
Gram + aerobe activity of Rifampin | Strep A, B, C, G, pneumonia,MSSA, MRSA, Coag(-),ornybacterium, listeria |
anaerobic activity of rifampin | NONE |
Gram - aerobe activity of rifampin | N. gonorrheae, meningitis, M. cararrhalis, H. influenza, F. tularensis, Brucella, bartonella henselae, |
Atypical activity of rifampin | Chlamydia, mycobacterium, leginella, Teberculosis, |
Gram + aerobic activity of nitrofurantion | Strep A, V, C, G, and pneumonia, MSSA, enterococcus |
Gram - aerobic activity of nitrofurantion | N. gonorrhoeae, E. coli, klebsiella, enterobacter, salmonella, shigella |
Anerobic activity of nitrofurantion | NONE |
Gram + aerobic activity of Chloramphenicol | Strep A, B, C, G, penumonia,MSSA, MRSA (some), enterococci, bacillus anthracis |
Gram + anaerobic | Actinomycetes, Clostridium, peptostreptococcus |
Gram - aerobes activity of chloramphenicol | Haemophilus, moraxella, aeromonas, salmonella, shiegella, e. coli, klebsiella, proteus, neisseria, vibria, brucella, yersina, pseudomonias (not aurginosa) |
Gram - anaerobes activity of chloramphenicol | Bacteroides, provotella |
Sulfonamides short to medium activity | Rapid absorption and elimination t1/2 11 hours |
Long acting sulfonamides | Only Silfathoxine used t1/2 100-200 hrs treatment for P. falcioarum |
Topical sulfonamides | Suldacetamide used in opthalamic and solutions |
Slufamethoxazole and trimethoprim clinical use | UTI, STD, FIRST LINE pneumonia, enteric infections |
Rifampin clinical used | Mycobacterial infections (pulmonary TB), Meningitis prophylaxis, Endocarditis, Meningitis |
Nitrofurantion clinical use | Uncomplicated UTI |
Chloramphenicol clinical use | Rarely used due to aplasic anemia which is not reversible!!!! |